DOHA, Qatar — Syrian opposition representatives took the country’s seat for the first time at an Arab League summit that opened in Qatar on Tuesday, a significant diplomatic boost for the forces fighting President Bashar Assad’s regime.

In a ceremonious entrance accompanied by applause, a delegation led by Mouaz al-Khatib, the former president of the main opposition alliance — the Western-backed Syrian National Coalition — took the seats assigned for Syria at the invitation of Qatar’s emir, Sheik Hamad bin Khalifa Al Thani.

Al-Khatib used the forum to call for a greater U.S. role in aiding the rebels and said he had appealed to Secretary of State John Kerry to consider using NATO Patriot anti-missile batteries in Turkey to help defend northern Syria against strikes by Assad’s forces.

The decision for the opposition to take Syria’s seat was made at the recommendation of Arab foreign ministers earlier this week in the Qatari capital, Doha. The Arab League in 2011 suspended the Syrian government’s membership in the organization as punishment for the regime’s crackdown on opponents.

The Qatari ruler, who chairs the summit, said the Syrian opposition deserves “this representation because of the popular legitimacy they have won at home and the broad support they won abroad and the historic role they have assumed in leading the revolution and preparing for building the new Syria.”

The diplomatic triumph and Qatar’s praise, however, could not conceal the disarray within the top ranks of the Syrian opposition.

Besides al-Khatib, the Syrian delegation included Ghassan Hitto, recently elected prime minister of a planned interim government to administer rebel-held areas in Syria, and two prominent opposition figures, George Sabra and Suheir Atassi.

Addressing the gathering, al-Khatib thanked the Arab League for granting the seat to the opposition. “It is part of the restoration of legitimacy that the people of Syria have long been robbed of,” he said.

He lamented the inaction of several foreign governments, which he did not name, toward the Syrian crisis and spoke emotionally of the suffering of the civilians in his country.

“I convey to you the greetings of the orphans, widows, the wounded, the detained and the homeless,” al-Khatib told the gathering in an opulent hall in Doha.

He also defended the presence in Syria of foreign jihadis, saying the militants were there to help defend a people under attack but adding that those more needed by their families in their own countries should leave.

“Is it the beards or the fact that they are foreigners?” he asked, referring to concern in the West and elsewhere that hard-line Islamic fighters are at the forefront of the battle against the Syrian regime.

“Why is no one saying anything about the Iranian and Russian advisers and Hezbollah?” he asked, a reference to opposition claims that the Syrian regime’s main allies are directly involved in the fighting.

Even as rebel fighters gain more territory on the ground in their fight against Assad’s troops, their mostly exile political leadership has been divided. Al-Khatib announced his resignation on Sunday because of what he described as restrictions on his work and frustration with the level of international aid for the opposition. The coalition rejected the resignation and al-Khatib said he would discuss the issue later and represent the opposition at the Qatar summit “in the name of the Syrian people.”

Also, Hitto’s election as the head of the interim government was rejected by the opposition’s military office, which said he was not a consensus figure. Some members have accused Qatar and the Muslim Brotherhood of imposing their will on the Coalition.

In Damascus, the government on Tuesday blasted the Arab League’s move to allow the opposition to take its seat at the Doha summit, portraying it as a selling-out of Arab identity to please Israel and the United States.